Innovative Rehabilitation: New Life for a 100-Year-old Steel Truss Bridge

摘要

The Dawson Bridge over the North Saskatchewan River has served the people of Edmonton, Canada for nearly 100 years. A five-span riveted steel through-truss, it was originally constructed to carry electric trains to a coal mine located on the east bank. Later converted to carry highway vehicles, the bridge currently accommodates 17,000 vehicles per day, along with significant pedestrian and cyclist traffic. In 2007, a bridge condition assessment revealed that the superstructure was in need of significant repair, including bridge deck replacement and truss repainting. Field inspection and structural analysis also identified numerous truss members requiring strengthening or replacement to provide an appropriate level of safety and extend the service life of the bridge. Presented as a case study, the paper includes the rationale for selecting the rehabilitation strategy for the bridge, along with the methodology by which truss members were identified for strengthening or replacement. The paper focuses on an innovative strategy for replacing the existing concrete deck with a composite steel plate and elastomer lightweight deck system. Also discussed is the inherent risk involved in the application of new technologies and the extensive risk control program that was implemented. Dawson Bridge is the first project in the world of this scale to incorporate this innovative deck system. Construction techniques for the installation of the prefabricated deck panels are described. Practical recommendations and lessons learned during the design and construction stages are also outlined.